Interim head coach Steve Spagnuolo of the New York Giants looks on in the first half against the Dallas Cowboys at MetLife Stadium on Sunday, Dec. 10, 2017 in East Rutherford, New Jersey. Photo Credit: Jim McIsaac

ST. PAUL, Minn. — Steve Spagnuolo is often credited for crafting the blueprint to beat the Patriots in a Super Bowl. He was the defensive coordinator for the Giants when they beat the previously undefeated juggernaut in Super Bowl XLII.

But the secret to his success may have been keeping it a secret.

Spagnuolo was a linebackers coach for the Eagles in Super Bowl XXXIX and said in a radio interview on Monday that he thought the Patriots were able to decipher Philadelphia’s play-calling during the game. That was two years before Spygate with the Jets, when the Patriots were found guilty of stealing signals from the sideline in 2007, and three years after the Patriots allegedly filmed the Rams’ walkthrough before Super Bowl XXXVI.

“The biggest thing we learned was make sure you have two signal-callers, not one signal-caller,” he told Philadelphia radio station 97.5 The Fanatic on Monday. “Because they may have all your signals.”

It wasn’t until after the Super Bowl game with the Eagles that Spagnuolo’s suspicion about the Patriots came forward.

Spagnuolo took that lesson with him into Super Bowl XLII. Using his defensive line to pressure Tom Brady has been seen as the key to Spagnuolo’s scheme in that game, but he has spoken about the equally important role of disguising coverages. The Giants knew Brady liked to snap the ball deep in the play clock, so the safeties would wait as long as they could before stepping into position for the play.

“I’m not crying over spilled milk here, but we believed that Tom knew when we were pressuring, because he certainly got the ball out pretty quick,” Spagnuolo said on Monday. “But, you know, you got to play the game, and they won that particular day.”